Maintaining a non-aligned status and being positioned geographically between the NATO nations and the USSR, Finland purchased military equipment from the East and the West alike. A second opportunity was during May 1954 when, in trade negotiations between Finland and the Soviet Union in Moscow, six MiG-15s were offered as part of the bilateral trade deal. A Finnish pilot was sent to make evaluation of the type. After flying a MiG-15UTI and evaluation of the fighter variant, it was found to be technically obsolete and unsuitable for the Finnish Air Force. The MiG-15UTI was also compared with the dh Vampire Trainer, which instead was selected as the first Finnish jet trainer during 1955.

The next time the MiG was on table was during 1956, when a new jet fighter type was being considered. This time the Soviet alternatives were the MiG-15bis or MiG-17. This time the Folland Gnat Mk 1 was selected. It took four years before the MiG-15 was offered again, as a trainer for MiG-19s the Soviets were trying to sell to Finland. This offer was again rejected, as the MiG-19S was found to be obsolete from both weapons and performance points of view. Following this dead end the study of western fighters, Mirage IIIC and Saab 35 Draken, was started. In this situation the Soviets changed their offer from the MiG-19 to the MiG-21F-13. As the purchase was possible to be paid with trade exchange and the MiG's performance was comparable with the Western types, the MiG was selected. Four MiG-15UTI trainer aircraft were added to the purchase as conversion trainers for the fighters - the reason was that the MiG-21 had no immediately available trainer version (the MiG-21U Mongol-A was just entering production in 1962). Agreement with the USSR was signed on 1st February 1962. Before delivery, a group of Finnish pilots and mechanics were trained in the Soviet Union in the latter half of 1962. The MiG-15UTI trainers were flown to Karelia Wing's Rissala base near Kuopio by Soviet pilots during November 1962. These planes were manufactured by Avia in Czechoslovakia and, according to manufacturing plates, these late production examples were type Avia CS-102.

Lauri Pekuri became the first Finnish pilot to fly the UTI-MiG-15 during a visit to Moscow as part of a military delegation. On 10th November 1962 the 31st Fighter Squadron (HävLv 31 Hävittäjä Lentolaivue, fighter squadron) at Kuopio-Rissala AB, which was part of the Karelian Air Wing (Karjalan Lennosto), took delivery of four Czechoslovak-built UTI-MiG-15s (Aero CS-102s). The aircraft, which were ferried amid great secrecy by Soviet pilots, were in the latest configuration, featuring the Afanasyev A-12.7 machine-gun, Bariy-M IFF and OSP-48 ILS. Interestingly, the trainers were diverted from the Soviet order but were nevertheless new aircraft, not second-hand machines.

The trainers received the tactical codes MU-1 (c/n 922221), MU-2 (c/n 822028), MU-3 (c/n 922226) and MU-4 (c/n 722375; sometimes reported in error as 722479); the MU serial prefix and the trainer's squat, tubby appearance promptly gave rise to the nickname 'Mukula' ('chubby' in Finnish). The aircraft were flown in natural metal finish. Each pilot converting to the MiG-21F-13 was given 14 flights (eight hours) in the UTI-MiG-15 before progressing to the fighter. The Midgets were also used for proficiency training. Additionally, the Air Force Flight Test Centre (Koelentuelentolaivue) at Halli AB undertook a short performance test program and used the Midgets for development work - for example, as radar targets for the Finnish Air Force's SAAB J-35S Draken fighters.

In 1968-69 the trainers underwent a major overhaul in the Soviet Union, but all other maintenance was done locally. MU-3 crashed on 27th November 1970 after running out of fuel, but the crew ejected safely. To fill the gap a fifth UTI-MiG-15 was procured, this time directly from Czechoslovakia. Since production had already ended it was a second-hand machine, a revamped Aero CS-102s (c/n 822210), a former ejection seat testbed with low flying hours, formerly operated by the Výzkumný a zkušební letecký ústav (VZLÚ, 'Czech Aerospace Research Centre') for the development of an indigenous ejection seat.

The revamped aircraft arrived in Rissala in early 1971 and received the new tactical code MU-5. This aircraft was insofar noteworthy as it became the only Finnish UTI-MiG-15 that carried camouflage. The scheme had already been applied in Czechoslovakia after a briefing from the Finnish Air Force, but the aircraft was delivered without tactical markings for the transfer flight. However, the requested paint scheme, an experimental camouflage reminiscent of the Finnish WWII scheme in green and black with grey undersides and "clouds" on the flanks that extended into the upper scheme, was executed with local paints, and following Warsaw Pact painting standards. As a result, the scheme was truthfully replicated, but the paints on the upper surfaces turned out to be rather dark. However, MU-5 was accepted with this unique livery and received large Ilmavoimat roundels in six positions (with the fuselage roundels close to the air intake), the tactical code on the flanks behind the wings, and the squadron badge (a leaping black lynx on a white cloud as background) on the fin, just below the stabilizers. Additionally, the aircraft’s callsign “Adam” was painted as a nickname and reminder for the trainees under the front cockpit opening. MU-5 retained its unique camouflage through later overhauls, even though refreshed with domestic paints that changed the upper tones into a lighter hue, and the tactical markings were changed over time, too. In the mid-Seventies the fuselage roundel on all Finnish Midgets was moved to the rear fuselage, the tactical code remained there but was reduced in size, and the lynx emblem was now painted behind the air intake, together with a single large number corresponding to the individual aircraft code.

The remaining three CS-102 veterans were kept in service until the small fleet was superseded by five MiG-21UM Mongol-Bs in 1978. These were, as an anecdotal note, delivered from the USSR in a dark camouflage very similar to MU-5 a couple of years earlier, due to the use of local paints and a rather free interpretation of the Finnish Air Force's paint scheme request! But with the arrival of the Mongols the Finnish UTI-MiG-15s’ career soon ended. MU-1 was struck off charge on 20th April 1979 and is preserved today at the Hallinportti museum just outside Halli AB. MU-2, which made its first flight in Finland on 12th January 1963 at the hands of Lt (SG) Veikko Tähtinen, was struck off charge on 30th May 1979 and is preserved at Vesivehmaa. MU-4 made its last flight from Rissala AB on 7th February 1977, piloted by Capt. Ari Piippo; it was struck off charge on 12th April 1979 and is now on display at the Central Finnish Aviation Museum (Keski-Suomen Ilmailumuseo) at Luonetjärvi airfield, Tikkakoski. MU-5, finally, was already lost on 15th of November 1977 in a ground fire that could be traced back to an oil leak in the engine section. The aircraft burned down beyond repair; since the airframe was even too damaged to become a museum exhibit it was eventually scrapped in 1979.